ABSRTACT Modal parameter identification based on wavelet transform has always been the focus of modal parameter identification of bridge. In order to solve the problem of arbitrariness and qualitative analysis in selecting wavelet function, a quantitative analysis index for modal parameters identification was proposed from the view of correlation, energy and entropy in the paper. Firstly, the continuous wavelet transform of vibration response signal for different wavelet functions was conducted. The correlation coefficients between the original signal and wavelet transform coefficients for different scales corresponding to one components of frequency was computed, and then the preliminary selection of wavelet function with large correlation coefficient was finished. Secondly, the index of the ratio of energy to entropy was introduced based on the criterion of energy and entropy. The wavelet function with maximum the index introduced was last selected. Finally, A numerical simulation of a system with 3 degrees of freedom was used to verify the proposed index, and the research result shows that the optimal wavelet function for modal parameters identification is the complex morlet function. Moreover, the wavelet function selected is used to identify the modal parameters of Z24 bridge and the suspension bridge and the results are coincided with the other ways, which verifies that the index is feasible.

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